High-speed growth of pentacene thin films by in-line organic vapor phase deposition

Abstract

Taking another step towards industrial production of devices based on organic semi-conductors, this work presents an extension of the organic vapor phase deposition technique to in-line geometry. A study of the in-line tool operation is carried out. It leads to the definition of a specific in-line deposition rate that qualifies the coating speed. It also allows for an understanding of processing parameter variations that lead to high deposition speeds. As a consequence, pentacene films are grown at in-line deposition rates of up to 1055μm²/s. This corresponds to web speeds of 2.1 m/min, equivalent to an average deposition rate of 105 Å/s in a static system. These films present a high uniformity, with a thickness standard deviation below 1.2% over 4 inch diameter substrates. Moreover, with transistor mobilities of up to 1.5 cm²/Vs, these pentacene films are of excellent electrical quality. This quality is conserved up to the highest deposition rates. Finally, 5-stage ring oscillators on foil based on a pentacene thin film deposited by in-line OVPD achieve a frequency of 24 kHz at a supply voltage of 20 V.